Let

Determine values for the constants such that

We compute the derivative,

Since we must have

From the equation on the left, equating like powers of we have,

From the equation on the right, equating like powers of we have,

Since and we have .

Since and we have .

Since and we have .

Finally, since and we have .

Putting these all together,

minor error : f is plus 2

I agree

Yes, f should be 2.